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a Carbuncle from its not being injured by the Fire; but that is ſtrange, for the Diamond[1] might as properly be for that Reaſon called by the ſame Name, as it alſo poſſeſſes that Quality.
- ↑ The Diamond has been thought to come neareſt of all Gems to deſerving the Character of incombuſtible. It will bear extreme Degrees of common Fire, and that for a long Time together, and come out unhurt. But it ſuffers ſome Damage, if ſuddenly brought into the Cold after theſe ſevere Trials; and much more by the Burning Glaſs. But there is yet a Quality which the Diamond ſhews in the Fire different from all other Gems, and by which it is diſtinguiſhed from them all; for there is a certain degree of Fire in which it is volatile. I ſhewed this, very many Years ago, to the late Excellent Lord Granard and Mr. Charles Stanhope, at my Houſe in Blomſbury; by placing a ſmall Diamond in a wind Furnace. We ſaw the Progreſs of the Operation: the Diamond was firſt penetrated by the Fire throughout its whole Subſtance; and appeared a burning Coal: it then ſhivered and cracked in many places, and afterwards became ſmaller and ſmaller till it entirely vaniſhed: no Part nor Remnant of it was to be found.
The Diamond is the hardeſt and moſt reſplendent of all Gems, and has in all Ages been eſteemed much more valuable than all others: its Colour, when pure, as it generally is, is that of perfectly clear Water; but it is ſometimes found tinged with metalline Par-
hard Gem, and is of a fine red, mixed with a violet Colour.
8. The Almandine; a Stone of a middle Nature, between the Ruby and Garnet. This is the Alabandicus of Pliny, and probably the Mileſian Carbuncle of our Author already deſcribed.
g. The Amandine. This was the Træzenius of the Antients, and was variegated with red and white; but is at preſent ſcarce known.
10. The Sandaſtrum of Pliny, a Gem now wholly loſt.
11. The Hyacynth of the Antients; truly and properly a violet-coloured Gem, and which, if it be now at all known, is ranked by the Moderns among the Amethyſts. The Stones we know by the Name of Hyacynths, being Gems of a yellowiſh red in three or four Degrees, which will be more particularly ſpoken of hereafter.
